I edit C++ code in .cpp files, while template code goes into .tcc files. When I open such a file, no syntax highlighting is available. I tried set syntax=cpp in a a tpp.vim file in ~/.vim/ftplugin/, but it does not do anything, while in the editor it works. Is there some way to have vim treat specific extensions as synonymous with others?

  • 1
    Very useful question! Thanks!!
    – rmbianchi
    Commented Feb 24, 2021 at 14:40

3 Answers 3


The preferred approach is to create a ~/.vim/filetype.vim, as mentioned in :help 43.2 and explained in Vim FAQ 26.8:

A better alternative to the above approach is to create a filetype.vim file in the ~/.vim directory (or in one of the directories specified in the 'runtimepath' option) and add the following lines:

" my filetype file
if exists("did_load_filetypes")
augroup filetypedetect
    au! BufRead,BufNewFile *.x       setfiletype c
augroup END


The did_load_filetypes shouldn't cause you any problems; it would only require a Vim restart after it is changed.

It is necessary in order to avoid multiple and unnecessary loading of this file, and it is inherited from the base file ($VIMRUNTIME/filetype.vim):

" Vim support file to detect file types
" Maintainer:   Bram Moolenaar <[email protected]>
" Last Change:  2014 Jun 12

" Listen very carefully, I will say this only once
if exists("did_load_filetypes")
let did_load_filetypes = 1

For more information check :help new-filetype.

  • Why the if statement? If I leave it in, the autocmds are not executed for me.
    – oarfish
    Commented Nov 10, 2015 at 14:28
  • @oarfish even if you restart Vim?
    – mMontu
    Commented Nov 10, 2015 at 15:05
  • Ok, this is weird. I have to au! statements in the group, namely au! BufRead,BufNewFile *.py setfiletype python and in the line below au! BufRead,BufNewFile *.tpp setfiletype cpp. But only the second one actually works. Editing .py files does not set the file type to python. I'm not exactly a vim-guru so I'm probably missing something.
    – oarfish
    Commented Nov 10, 2015 at 15:11
  • @oarfish if you check the file I mentioned on the edit you will find that it already contains a line with au BufNewFile,BufRead *.py,*.pyw setf python, so your first line is irrelevant. Your problem is probably elsewhere.
    – mMontu
    Commented Nov 10, 2015 at 15:16
  • "Editing .py files does not set the file type to python" - what is the output of :set ft on that case? If it is not python, try following the procedure in Vim-FAQ 2.5 - I have a "xyz" (some) problem with Vim
    – mMontu
    Commented Nov 10, 2015 at 15:20

You could do (in your global .vimrc):

autocmd BufEnter *.tpp :setlocal filetype=cpp
  • autocmd BufEnter *.cuf :setlocal filetype=fortran to treat CUDA Fortran files as Fortran
    – khaverim
    Commented Jan 27, 2018 at 18:38
  • 2
    If you have multiple files you want to associate with a language, delimit the patterns with commas and no spaces between the commas: autocmd BufEnter *.tsx,*.jsx,*.ts :setlocal filetype=javascript
    – ggorlen
    Commented Jan 9, 2020 at 23:20
  • Upvoted this answer because it works directly from the .vimrc file. Commented Mar 23 at 13:44

One could also have: au BufRead,BufNewFile *.tpp setlocal filetype=cpp in their .vimrc such that upon opening a file with .tpp extension, filetype is set for C++

  • 1
    This seems to be basically identical to @edi9999's answer. Can you elaborate on why to use BufRead,BufNewFile instead of BufEnter?
    – oarfish
    Commented Sep 5, 2018 at 10:02
  • 1
    @oarfish It doesn't matter too much I think, but I prefer BufRead,BufNewFile ahead of BufEnter because in the docs (:help BufEnter) it states: "BufEnter: .... Also executed when starting to edit a buffer, after the BufReadPost autocommands." where BufReadPost is synonymous with BufRead. In addition, I do not believe the : is required before setlocal so I also omitted that in my answer. (I might have interpreted this completely wrong, happy to hear further discussion)
    – tallamjr
    Commented Sep 5, 2018 at 10:50

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